1. Field of the Invention
The present invention concerns a method for planning an angiographic (image acquisition) measurement of a body region in a magnetic resonance system (MR system) as well as the MR system for this.
2. Description of the Prior Art
As has long been known, in MR imaging, is sensitive to the movement of the nuclear spins that generate the MR signal. These effects can be used for acquisition of angiographic images, i.e. images of the vessels of the examined person. Angiographic techniques are known that are based only on the flow effects of the spins located in the body. Furthermore, it is possible to improve such angiography acquisitions with the aid of contrast agents. Given use of a contrast agent, for the angiographic representation of vessels over a larger anatomical region in the body it is difficult to track the contrast agent introduced into the vascular system in real time given passage (flow) through the examined region.
It is hereby important to temporally match the procedures for all acquisitions to one another in order to optimally depict the vessels in each body region. In angiography acquisitions these are also matched to each patient since the individual circulation time of each patient changes the passage speed of the contrast agent. When very large vessel segments (such as, for example, the entire vascular tree in the body) is to be depicted, this often cannot be accomplished with a single contrast agent injection. This particularly applies when the contrast agent flows relatively quickly through the body.
The apparatus operator is thereby required to individually adapt the measurement parameters for the imaging, but this results in many possible sources of error. For example, that the image quality is degraded by the adaptation of the acquisition parameters (such as the shortening of the acquisition duration) in order to be able to track the contrast agent course. Experientially, combining all of the measurement parameters dependent on one another such that a good image quality is always achieved causes problems for the users of MR systems. The temporal sequence of the acquisition is often incorrect, such that it can occur that the images display not only the arterial image information that is important for the diagnosis finding, but also display signal contributions of the venous (return) flow of the contrast agent. It is likewise possible that the image quality is not sufficient to allow the diagnosis when the parameters of the spatial resolution vary too severely for different measurement regions.
Overall this acquisition technique requires a great deal of knowledge on the part of the operator, so the image quality depends very strongly on the experience of the person who implements the angiographic measurement.